Every impression counts in digital advertising, and businesses need to know how much they spend to reach their audience. 

CPM, or cost per mille, is a fundamental metric all advertisers should know because it tells them how much they spend to reach one thousand viewers. 

By understanding CPM, you can determine whether you’re getting your money’s worth and make better decisions about where to invest your advertising dollars. 

What is CPM?

CPM, short for cost per mille, is a popular metric in advertising. It calculates how much it costs to reach a thousand views or impressions of an ad.

CPM is used in online advertising, where advertisers pay for ad space based on the number of times their ad is shown, regardless of clicks or actions taken by viewers. This metric can help you compare the cost-effectiveness of different ad channels and campaigns. 


CPM and CPC (cost per click) are two pricing models used in online advertising. They each offer distinct advantages depending on your campaign goals and target audience. 

CPM involves paying for impressions. This means advertisers pay a set rate for every thousand times their ad is displayed to users, regardless of how users engage with it.

CPC, on the other hand, entails paying for clicks. This means advertisers are charged only when someone clicks on their ad, regardless of how many times the ad is displayed.

The choice between CPC and CPM depends on your campaign objectives and target audience behavior. CPM is best for brand awareness campaigns because it ensures maximum exposure to a large audience without necessarily driving immediate actions. 

In contrast, CPC Is suitable for campaigns focused on driving traffic or conversions, as advertisers only pay when users actively engage with the ad. 

Factors to consider when choosing between CPM and CPC ads include: 

  • Campaign goals: Do you want to increase brand visibility, reach a broader audience, or drive specific actions like clicks or conversions? 
  • Budget constraints: How does the budget align with the pricing models? Are you comfortable paying for impressions regardless of clicks or do you prefer to pay only when users engage with the ad? 
  • Characteristics of the target audience: Is the target audience more likely to passively consume content without taking immediate action, or are they actively searching for products and likely to click on ads?

How to calculate CPM

To calculate cost per mille, you can use the following formula: 

      CPM = cost of campaign / number of impressions x 1000

  • Cost of the campaign: The total cost incurred for running the advertising campaign. 
  • Number of impressions: The total number of times the ad was displayed to users during the campaign period

Optimizing your CPM: Tips & tricks

Reducing your CPM lowers your cost of reaching more people, making your advertising campaigns more cost-effective. 

Here are a few strategies to enhance your CPM marketing strategy and reduce your CPM. 

Improve ad relevance

Create high-quality, engaging ad content that resonates with your target audience. 

Relevant ads are more likely to generate interest and interactions, which can improve ad performance metrics and lead to lower CPM rates.

Refine audience targeting

Fine-tune your audience targeting parameters to reach the most responsive segments. 

By narrowing down your target audience based on demographics, interests, and behaviors, you can minimize wasted impressions and optimize the efficiency of your ad spend, leading to lower CPM rates.

Test different ad formats and placements

Experiment with ad formats, sizes, and placements to identify the most cost-effective options. 

For instance, you can try in-feed or conversation placements and different ad types like image, carousel, free-form and video ads on Reddit. 

Testing different strategies allows you to optimize ad performance and maximize the value of each impression, ultimately reducing overall CPM rates.

Increase ad frequency

Increase the frequency of your ads to ensure a larger portion of your target audience sees them as part of your target audience. 

Boosting exposure and impressions due to higher volume commitments can help you command lower CPM rates with ad networks for publishers.

Maximize your reach and ROI with CPM

By understanding the basic principles behind CPM ads and using techniques to reduce costs and enhance performance,  you can achieve greater engagement for less. 

Get started with Reddit Ads today to use CPM-based pricing models and achieve specific campaign objectives. Whether aiming to increase brand awareness or drive engagement, Reddit Ads offers versatile options for reaching your target audience.